الفهرس 
Highway bridge structuresOnly 14 pages are availabe for public view
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Abstract
the four-point bending tests conducted on the BFRP and hybrid reinforced beams. This section also includes the recommendations that can be made based on the conclusions drawn from the analysis conducted from the test data obtained from the tests. The conclusions can be subdivided into the following based on the nature of analysis performed. 1. The pre-cracking response and cracking loads of the first group beams were nearly unaffected by the reinforcement ratio.However, increasing BFRP reinforcement ratio has significant effect on post- cracking stiffness and the serviceability of the beams . The deflection of beams B-2-0,B-3-0 ,B-4-0 and B-5-0 at service load (30%Pu) was 9.5 ,9.0 ,6.0 and 4.0 mm respectively and the allowable deflection is L/240 =9.2mm according to ACI440.1R-15. This shows that beams B-3-0, B-4-0,B-5-0 with reinforcement ratios =0.87,1.16 and 1.45% respectively satisfied serviceability requirements for deflection . 2. The BFRP-RC beam with the lower reinforcement ratio =.58% showed sharp increases in strains and deflection at cracking. The sudden increase in strains resulted in wider and deeper cracks, which is reflected on the stiffness and the location of the neutral axis of the cracked section. 3. The ultimate load capacity for beams B-2-0, B-3-0,B-4-0and B-5-0 was 118,132,145 and 165 kN respectively . This showed that increasing reinforcement ratio by 150% (B-2-0 to B-5-0) caused an increase in the ultimate load by 40% .Comparing beam B-3-0 with B-2-0 , as the reinforcement ratio increased by 50% the ultimate load increased by 12% .Comparing beam B-4-0 with B-2-0 , as the reinforcement ratio increased by 100% the ultimate load increased by 23%. Comparing beam B-5-0 with B-2-0 , as the reinforcement ratio increased by 150% the ultimate load increased by 40%.This showed that the rate of change in load capacity was almost constant for the same increment ratio of reinforcement . 4. The deflection at ultimate for beams B-2-0, B-3-0,B-4-0and B-5-0 was 55.0,45.0,27.0 and 22.0 mm respectively . This showed that increasing reinforcement ratio by 150% (B-2-0 to B-5-0) caused a decrease in the ultimate deflection by 60% . 5. The crack width at service load level for beams B-2-0 ,B-3-0, B-4-0 and B-5-0 was 0.7mm,0.5mm,0.4mm and 0.3mm respectively and the maximum allowed crack width at service load is 0.5mm for flexural members reinforced with FRP bars according to ACI440.1R-15. This showed that beams B-3-0,B-4-0 and B-5-0 with reinforcement ratios = 0.87,1.16 and 1.45% respectively satisfied serviceability requirements for crack width limit according to ACI440.1R-15 . 6. Serviceability criteria can be achieved by increasing the area of BFRP reinforcement. However, the ultimate failure could be occurred without prior warning because the crack depth and width decreased when the area of BFRP reinforcement increased. Therefore, establishing the maximum BFRP reinforcement area would be much important. 7. For hybrid beams, there is a nonlinear stage took place after steel yielding. Therefore, the hybrid system can overcome the ductility problems for concrete beams reinforced with BFRP bars .Adding steel bar of diameter 10mm to the beam B-2-0 and B-3-0, led to enhance the ductility .The ductility index for the beams B-2-1 and B-3-1 was 1.6 and 1.3 respectively .This indicated that the ductility index decreased when BFRP to steel ratio increased . 8. A numerical model using commercially available finite element program “ANSYS® 15” was developed and evaluated . All the experimental results were compared to the numerical results, in order to validate the numerical finite element model. Comparing results between experimental and numerical proved that the model could expect accurately the ultimate failure loads, the load–deflection curves and the mode of failure for BFRP-RC beams and hybrid beams . 9. A parametric study was conducted to estimate the maximum BFRP reinforcement ratio in case of different concrete strength batches . Also a regression analysis was carried out to estimate the best fit equation to get the maximum reinforcement ratio for concrete beams reinforced with BFRP bars as a function of concrete strength .